78
Operation
SP 500 / 750-15 / 750-18 / 1000 / 1250 Operation Manual
Time constraints
Remember, if anything goes wrong on the unit while it
is pumping, you only have 15 to 30 minutes to solve the
problem before the concrete sets. (Less with old con-
crete on a hot day, more with fresh concrete on a cool,
cloudy day). If you know that it will take longer than 30
minutes to x the problem, clean out before you begin
repairs. If concrete is beginning to set, you will have
to clean out in a very quick an ecient manner. There
are special instructions which you will nd in the Opera-
tion section of this manual. If you don’t panic and keep
moving, you can usually avoid cleaning or replacing the
pipes. Old concrete and hot days is the worst case sce-
nario. Under certain hot weather and old concrete cir-
cumstances, the concrete may go from being pumpable
to setting very, very quickly. This is called ‘ashing’, and
if it happens, you may lose some pipe. See also the
section on delays described in the “” on page 85.
Cold conditions
Always keep the hopper at least half full. If any prob-
lem arises with the unit while it is pumping, you have
just 15 to 30 minutes to solve it before the concrete be-
gins to set, and possibly less time if the temperature is
extremely cold. If you know you will need more time,
clean out before you begin repairs. If the concrete is
beginning to set or freeze, you will have to clean out
quickly and eciently. Review the special instructions
for quick cleanout and delays in the Operation section
of this manual.
Delays
Expect delays on the job. Sometimes you will have to
wait for concrete. Sometimes the workers will need to
nish the next form to be pumped. Sometimes a form
will fail. You can make good use of this idle time by
washing pipe, clamps, and gaskets that have been
removed from the delivery system, washing splashed
concrete from your hopper area, eating lunch, or taking
care of miscellaneous tasks. Remember that concrete
begins to set as soon as it becomes motionless. Ev-
ery 5 minutes or so, give the pump a stroke. This will
make the concrete in the elbows and reducers change
its shape, thus breaking the set. Concrete setting in the
pipeline acts like a blockage. Blockages can be danger-
ous, because the pump will create maximum pressure
on the concrete. Always keep the hopper at least half
full. If the concrete is getting sti, add water to the hop-
per while you are waiting. A word of warning regarding
this procedure: The concrete will eventually set up any-
way. If you wait so long that the concrete is setting, it is
a good idea to clean out and then start over when the
fresh concrete has arrived.
• If you are waiting for a form to be nished or re-
paired, or anytime that the delay has nothing to do
with waiting for concrete, you can give the pump
one or two strokes in 5 minute intervals for a lon-
ger time, because the ready-mix truck will be able
to rell your hopper. Be careful about where the
concrete is going when you are giving the ma-
chine these one- or two-stroke cycles. If the form
is broken, you will complicate matters by putting
more concrete in it.
• Eventually, you will have to make the call; once
concrete begins to set while it is being pumped,
you have only minutes to get the machine cleaned
out. For this procedure, see “Cleanout.”
• Another thing to consider is the condition of the
concrete in the ready-mix trucks. If three or four
trucks have been waiting on the site for a period of
time, their concrete may be setting up. If it is a hot
day and the concrete is setting up, you are risking
a pipe cleaning party by pumping this concrete.
The concrete pump operator must make the deci-
sion to use or not to use this concrete.
Keep the water box full
Remember to check the water in the waterbox regularly
(stopping the pump before opening the waterbox cov-
ers). Water is very important for cooling the dierential
cylinders and for lubricating the rubber rams.
Under no circumstances should you remove the hop-
per grate while the machine is operating, nor should the
machine be operated when the grate is not in place. If
your grate is in place, it will catch all types of foreign
objects: mixer ns, clumps of unmixed cement, cats,
dogs, rebar, golf clubs, tools of all sorts, and so on. If
any of these items made it into your hopper, they would
probably cause a blockage, which is always dangerous.
Amputation/crushing hazard. Keep
hopper grate in place during opera-
tion and cleaning.
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